The Coalition’s advisors on school food said head teachers should prevent pupils bringing their own lunches into school – and ban them from visiting fast food outlets – amid continuing fears over the state of children’s diets.

It was claimed that the move would effectively force parents to pay for school dinners – allowing staff to spend more money upgrading kitchens and generating healthy canteen food.

Ministers have already agreed to introduce compulsory cookery classes for seven- to 14-year-olds under a newly revamped National Curriculum.

From 2014, children will receive new lessons in nutrition and cooking techniques, eventually building up a repertoire of 20 dishes by the time they leave secondary school.

Henry Dimbleby and John Vincent, co-founders of the Leon restaurant chain, who have been appointed to lead a review of school meals, said the move would improve children’s understanding of the importance of a healthy diet.

But they suggested that more radical action may be needed to boost standards of food consumed in schools themselves over lunchtime.

Mr Dimbleby said: “There’s still too much processed food in school canteens. Some of the meals I ate were a bit institutional – meat and two veg – and there is undoubtedly work to be done.”

Currently, around 40 per cent of children eat school meals, with the remainder bringing in packed lunches or leaving school at lunchtime to visit local fast food stores.

Speaking to The Sunday Times, Mr Dimbleby, son of the broadcaster David Dimbleby, said schools should consider banning packed lunches and requiring pupils to remain on site over lunch to drive up investment in school catering services.

He suggested billions of pounds was needed to enable all schools to provide high-quality healthy options for pupils.

“What we need to do is lift uptake from 40 per cent to 80 per cent over five years to make school meals solvent again,” he said. “Rather than ask government to subsidise a structurally bust system, we want the system to become solvent by getting more customers to pay for school dinners.”

Mr Dimbleby said that head teachers should effectively police packed lunches themselves, considering an all-out ban or restrictions on the type of food that can be included. This would prevent parents sending children to school with sugary and high-fat food.

“Because of the criticism school dinners underwent, there is a legacy in our minds as parents that you are going to feed your kids bad food if you give them school dinners,” he said. “But that is not true because scientific analysis shows cooked meals are healthier than packed lunches.”